(a) Field of the Invention
The present invention relates to a field emission display. More particularly, the present invention relates to a field emission display that includes a mesh grid, and a manufacturing apparatus and a manufacturing method of the field emission display.
(b) Description of the Related Art
A field emission display (FED) is a flat panel display configuration that typically uses cold cathodes as electron emission sources to realize the display of images. FEDs generally employ a diode structure that includes cathode electrodes and anode electrodes, or a triode structure that includes cathode electrodes, anode electrodes, and gate electrodes.
A FED that employs a triode structure is described with reference to FIG. 13. The FED includes a rear substrate 1 and a front substrate 3 provided substantially in parallel with a predetermined gap therebetween. An emission structure for emitting electrons is formed on the rear substrate 1 and a phosphor structure that is excited by the emitted electrons is formed on the front substrate 3. Spacers 5 are provided between the substrates 1 and 3 to maintain the gap therebetween. The rear substrate 1 and the front substrate 3 are sealed in a state where a vacuum is formed in the gap between these elements.
In more detail, electrons are emitted from electron emission sources 9 by a difference in voltage applied to cathode electrodes 7 and gate electrodes 15. Also, a high voltage is applied to anode electrodes 11 such that the electrons are accelerated toward phosphor layers 13. The electrons strike the phosphor layers 13 to excite the same.
During the above operation, it is possible for arc discharge to occur within the FED by the high voltage applied to the anode electrodes 11 and the small gap (i.e., cell gap) between the substrates 1 and 3. If a short occurs between the gate electrodes 15 and the anode electrodes 11 as a result of such arc discharge, the high voltage of the anode electrodes 11 is applied to the gate electrodes 15 which may damage a drive circuit of the FED.
To prevent this problem, a grid substrate may be mounted between the rear substrate 1 and the front substrate 3. The applicant discloses a metal grid as a grid substrate in Korean Laid-Open Patent Application No. 2001-0081496. The metal grid (indicated by reference numeral 17 in FIG. 13) is a mesh grid electrode made of metal.
The metal grid 17 is low in cost (compared to other types of grid substrates that are made of photosensitive glass) and is easily made in large sizes. However, manipulation of the metal grid is difficult. For example, it is difficult to adhere the metal grid 17 to a glass substrate, that is, the rear substrate 1 and the front substrate 3.
Further, to mount the metal grid 17 in a flat configuration to a substrate, it is necessary that the metal grid 17 be formed to a thickness that exceeds a predetermined amount. However, it is difficult to form the metal grid 17 to a thickness that is greater than or equal to 100 μm in order to allow for the formation of minute holes (of a diameter of less than or equal to 100 μm) by a chemical etching process.
The metal grid 17 is generally made of an alloy stainless steel sheet that contains chrome (for example, a 42-6 alloy—42% Ni, and 6% Cr, Fe, etc.). When attaching the metal grid 17 formed in this manner to a glass substrate, in order to securely and closely attach these elements, a blackening process is performed on the alloy stainless steel sheet to form an oxidation film on its surface, after which a crystallized glass (frit) is used as an adherent to attach the metal grid to the glass substrate through a baking process.
The two different types of oxidation materials used for the oxidation films include the spinel-type oxidation material (Mn,Fe)O.Cr2O3 and the corundum-type oxidation material (Cr2O3). With respect to the spinel-type oxidation material, part of the oxidation material frit is diffused to increase the chemical attraction between the oxidation film and the frit, and with respect to the corundum-type oxidation material, the airtight seal and contact strength between the parent metal and the oxidation film are increased.
Accordingly, when the metal grid is heat-treated or is otherwise manipulated (e.g., attached to other elements), there is a high possibility that the metal grid will be deformed. Therefore, in the prior art FED described above, the metal grid is securely mounted, then spacers are provided in the FED to maintain the cell gap between the substrates.
However, since the spacers are mounted passing through the metal grid, it is possible for the spacers to be misplaced by the different degrees of thermal expansion between the glass substrate and metal grid or by shock given to the FED during assembly. This may result in the metal grid sagging or otherwise becoming deformed.